Unit 12: The Search for Life in the Universe

What is the “Great Moon Hoax?”

• article series finding Moon life

What explains the Moon’s lifelessness?

no radiation

• no radiation protection

• no heat retention

What was the unmanned lander sent to the Moon surface in 1967?

Surveyor 3

What was Apollo 12’s instruction?

bring Surveyor 3 back

• commander Pete Conrad dismantled lander & placed in sterile container

What did they find on the Surveyor 3?

live bacteria

• streptococcus

What is an “extremophile?”

lifeform surviving extreme conditions

What is the most likely lifeform to be found in our Solar system?

extremophile

What is the “HZ?”

Habitable Zone / Goldilocks Zone

star distance at which planet can sustain liquid water on surface

What is in the Sun’s Habitable Zone?

• Earth

What limits the Habitable Zone?

• heat planet receives

• star mass

What does carbon’s ability to form complex molecules suggest?

carbon life = common

What explains Earth’s carbon life?

act as complex molecule glue

• 4 outer e- bond with up to 4 other atoms

  • no other star atom can bond with as many atoms

  → amino acid → protein

What is an “amino acid?”

life building block

What could be former Mars liquid water evidence?

• polar icecaps contain 50% water-ice

• canyon = ancient river

What explains Mars’ dried water?

thin atmosphere

What did NASA send robotic landers to Mars in the 1970s to study?

Viking 1 & 2 studied soil samples for carbon life evidence

What did NASA conclude from the Vikings?

no Mars life

What did simulated Mars soil find in the 1990s?

live microorganism

What method did simulated Mars soil use to find live microorganisms?

radioactive tagging

• metabolized nutrients

What was found in Allen Hills, Antartica, in 1984?

Martian meteorite ALH84001 containing fossilized carbon microorganism

What did NASA’s Opportunity rover find, landing in 2004?

water-reposted mineral vein in Mars rock

• hydrated calcium sulfate

What did NASA’s Phoenix lander find, landing in 2008?

polar ice, carbon, & minerals

What did NASA’s Curiosity rover study, launching in 2011 & landing in 2012?

soil beneath surface

• smooth pebble

• warmer & wetter conditions

  • global liquid ocean water

What is NASA’s Perseverance’s mission?

look for ancient life & collect rock

What Solar System moons show potential habitability?

• Europa

• Titan

• Enceladus

What did NASA’s Galileo orbiter find on Europa in 1995?

cracked icy surface

What possibly caused Europa’s cracked icy surface?

liquid ocean underneath

• warmer temperature

What possibly causes Europa’s elevated internal temperature?

Jupiter & largest moons’ gravity

• constantly pulled

  → heat friction

What evidence of Europa’s liquid ocean was found in 2019?

water jet ejected from surface

What was NASA’s Galileo end?

burnt in Jupiter atmosphere

What missions have space agencies proposed to Europa?

• underwater probe life search

• Europa Clipper

What did NASA’s Cassini send to Titan, arriving at Saturn in 2005?

Huygens probe

What did Huygens find on Titan in 2005?

• thick hazy atmosphere

• carbon-rich methane lakes

• possible ice volcanic activity spewing water / steam / methane

What is the only other Solar System body that has liquid on its surface?

Titan

What did NASA’s Cassini find from Enceladus?

water / rock & carbon plumes

→ global liquid ocean water

What could Enceladus’ rock & ice mix indicate?

hydrothermal vents at ocean bottom

What mission has NASA announced to Titan, launching in 2026 & landing in 2034?

Dragonfly drone

What did American astronomer Frank Drake organize in 1961?

Green Bank Conference

What did Frank Drake do in 1960?

SETI

What is the “SETI?”

Search for Extraterrestrial Intelligence

program listening for ET radio

What was the “Green Bank Conference?”

private conference

• published theories about how to search for intelligent extraterrestrials

What signal did SETI receive at Ohio’s Big Ear Radio Telescope in 1977?

Wow! signal

What is the “Wow! signal?”

loud radio burst

• could not attribute to known source

What did SETI’s restarted Project Phoenix listening program use radio dishes around the world to monitor?

800 near Sun-like stars for ET radio

What was US government response to SETI in 1993?

canned

What explained why US government canned SETI in 1993?

no result

What is the “SETI Institute?”

private SETI research organization

• private funding

What is Project Phoenix’ director name?

Jill Tarter

What did Project Phoenix do in 2004?

stop

What did SETI build in the early 2000s?

Allen Telescope Array

• $30 000 000 private donation

What is “Breakthrough Listen?”

private campaign monitoring 1300 near stars

What is the “Drake Equation?”

communicating Milky Way civilization estimate

[N = R* ⋅ f_p ⋅ n_e ⋅ f_l ⋅ f_i ⋅ f_c ⋅ L]

• unsolved

What did Frank Drake develop in 1961?

Drake Equation

What does R* represent in the Drake Equation?

average annual star formation rate

• 1

  • estimate based on gas amount

What does f_p represent in the Drake Equation?

fraction of stars that have planets

• 50% - 100%

What does n_e represent in the Drake Equation?

average planets per star capable of sustaining life / having surface liquid water

• 50% in HZ

  • Kepler Space Telescope exoplanet analysis

• 1

  • Solar System

What does f_l represent in the Drake Equation?

fraction of n_e planets where life evolves

• 50%

  • extremophile

What does f_i represent in the Drake Equation?

fraction of f_l where intelligent life evolves

• 10%

  • unintelligent life > intelligent life

What does f_c represent in the Drake Equation?

fraction of f_l that has means & desire to communicate

• 100%

  • all intelligent life would attempt

What does L represent in the Drake Equation?

average communication lifetime

• 10 000 years

  • Frank Drake recommended value

What was the SETI Institute’s response to completing Arecibo dish construction?

send Arecibo Message to globular cluster M13

• 25 000 lightyears

What did Earth send into space in the 1970s?

Earth & human info

• Arecibo Message

• Pioneer plaque

• Voyager Golden Record

What is the “Arecibo Message?”

radio blip series

What are the “Pioneer plaques?”

2 Pioneer 10 & 11 spacecraft engravings

What is the “termination shock?”

bubble around Sun

• inward & outward charged particles → front in space

What were the Pioneer & Voyager spacecrafts’ mission?

explore outer Solar System & study boundaries & enter interstellar space

• 2 million years to reach stars

What are the Pioneer plaques’ & Voyager Golden Records’ basic unit?

hydrogen light wavelength

• spin flip

What is the “Voyager Golden Record?”

Voyager 1 audio record & engraving

What was the 1st manmade object to explore interstellar space & cross heliopause on August 25, 2012?

Voyager 1

• 40 000 years to approach star from 2 lightyears

What is the “heliopause?”

point where Sun solar wind pressure = interstellar space pressure

What SpaceX spacecraft was launched to study the outer solar system & Pluto in 2006?

New Horizons

What was New Horizons not given to deliver to cosmos?

message

What method did Paul Butler & Geoff Mercy use to find the 1st exoplanet?

Doppler Wobble Method

What is the “Doppler Wobble Method?”

Radial Velocity Method

starlight spectrum Doppler shift search

What explains the Doppler Wobble Method?

planet gravity causes star to wobble around centre of mass

→ wavelength shift reveals planet period & orbital radius & mass

What does negative radial velocity show about motion?

approaching

What does positive radial velocity show about motion?

receding

What explains why Paul Butler & Geoff Marcy could not initially tell they observed stars with planets?

not looking for rapid enough wobbles

• 51 Pegasi planet had 5 day orbital period

What did Swiss astronomers Michael Mayor & Didier Queloz detect in 1995?

1st exoplanet

• orbit around 51 Pegasi

What is a “Hot Jupiter?”

gas giant near star

What explains why the Doppler Wobble Method kept finding Hot Jupiters?

massive planet close to star = large star wobble

What explains why Hot Jupiters do not appear to be conducive for life?

not enough matter to coalesce into Jupiter-size planet

• Hot Jupiters formed far & migrated inward until stable orbit

inner planets would get disrupted

What have recent studies found about Hot Jupiter migration?

if very early in solar system lifespan, Earth-like planet could form after migration

What was NASA’s Kepler Space Telescope mission, launched in 2009?

monitor sky near Cygnus constellation

• just above Galaxy disc

What is the “Kepler Space Telescope?”

solar orbiting spacecraft finding Earth-size planet

What method did the Kepler Space Telescope use?

planetary transit method

What is the “Planetary Transit Method?”

eclipsing of star by planets

→ periodic star dim

What does the Planetary Transit Method dim period & depth reveal?

planet period & orbital radius & size & temperature

What are most Kepler Space Telescope false positives?

eclipsing binaries

What explains why the Doppler Wobble Method confirms exoplanets?

measure object mass

• Kepler law & Newton gravity

What caused the Kepler Space Telescope end in 2018?

lack of fuel

What are some Kepler Space Telescope top results?

• Galaxy planets > stars

• small planets = common

• most common planet type is not found in Solar System

What is a “Super Earth?”

planet between Earth & Neptune size

What is the transit signature dip depth & planet size relation?

big planet = block a lot of starlight

What is the solar system naming convention?

• A = star

• successive letters = discovery order

What is an example of an Earth-like planet?

• Kepler-186f

What is the “TESS?”

Transmitting Exoplanet Survey Satellite

look for exoplanets all over sky

• 2000+ candidates in 2 years

What is next in Earth-like planets & life?

• SETI listens for intelligent radio

  • common Earth-like planets

• NASA investigates Earth-like atmosphere spectra

  • produce while it is & not transitted

  • subtract